Conventionally, it has already been known that tubular body having section of circular, elliptic or similar form with these is formed with elastic material such as rubber or elastic plastic, and such a tubular body is utilized as a shock absorbing structure such as fender for vessels or bumper for vehicles.
And, also in designing a tubular body member having such a shock absorbing function, researches on the structure or sectional shape of member have been continued from long time ago for the purpose of improving durability and further enhancing shock absorbing function of member even while sectional area of member is reduced as far as possible whereby dimension of product and manufacturing cost are decreased, as a result, various ideas have been proposed. For example, techniques related to bumper for vehicles can be cited which are respectively disclosed in British Patent No. 1562254 granted to Aurelio Brollo of Italy and in U.S. Pat. No. 4,320,913 issued to Shigeharu Koroda of Japan. That is, in these patents, technique related to a bumper for vehicles is disclosed in which in forming tube tubular body with elastic material such as rubber or elastic plastic, shock absorbing structures with several partitions arranged within hollow of said tubular body so as to be crossed in X-shape by intersecting said hollow or in radial shape is formed integrally through lengthwise direction of the tubular body whereby toughness and restorability are increased, so that excellent shock absorbing capacity is included against highly shocking load even if a shock is applied from any direction.
And, a rubber bumper is known in which shock absorbing structures having different structure relative to that in aforementioned two patents is integrally formed within tubular body of circular or elliptic shape in section made of anti-elastic material, in international patent application PCT/KR85/00013 which is filed by the inventor of this application on Jun. 4, 1985 and published by International publication No. WO86/00051 on Jan. 3, 1986.
However, since the shock absorbing structure having structures as described above is designed suitably for utilizing as bumper for mainly vehicle, it is not suitable as a structure of fender for utilizing in medium or large vessels. A shock absorbing structure capable of equally using from small vessel to large or super large vessel is required in the case of fender for vessel, and since shocking load to be applied to the fender is also applied with further larger big load relative to the case of bumper for vehicle from irregular direction, a shock absorbing structure capable of absorbing effectively such a high shocking load is required.